…the Percona Live MySQL Conference & Expo 2013 the week before last, we quietly …bulk-insert may corrupt data pt-heartbeat –utc –check always returns 0 pt-query-digest 2.2 prints unwanted debug … prints the wrong variable name in verbose mode when –function is used And more The first two bugs are …
Post: Percona Toolkit 2.2.2 released; bug fixes include pt-heartbeat & pt-archiver
May 6, 2013 By 2 Comments
Post: Replication of the NOW() function (also, time travel)
November 28, 2012 By 6 Comments
…Notice the result of the NOW() function in the following query. The query was run on a … the NOW() function return a value in the past? The “secret” is the TIMESTAMP variable, which is a special MySQL variable that can… returns the correct date. This means the SYSDATE() function is not replication safe by default. If you want to use the SYSDATE function…
Post: Testing MySQL column stores
August 16, 2010 By 15 Comments
… first first part of my analysis focused on testing specific MySQL functionally with Infobright’s storage engine. A lot of my tests… aggregate functions as ICE, and therefore it could not run some of the queries. ICE supports almost all of the MySQL aggregation functions… “select count(*) from carsales.sales_fact” when run on InfiniDB returned a number that was higher than it should have been…
Post: Upgrading MySQL
January 5, 2010 By 24 Comments
… projects. Why is that ? Performing MySQL upgrade two things should normally worry you. It is Regressions – functionality regressions when what you’ve… work differently after change. For example you may get queries returning different result or getting different execution plan, taking minutes or… is safest if you’re running application which uses simple MySQL functionality which is unlikely to be affected. If you’re something…
Post: Statement based replication with Stored Functions, Triggers and Events
December 16, 2011 By 4 Comments
… is the behavior of the MySQL when it needs to log “not usual” queries like Events, Functions, Stored Procedures, Local Variables, etc… will stop with an error. Example: mysql> CREATE FUNCTION this_year() RETURNS INT DETERMINISTIC RETURN YEAR(CURDATE()); mysql> insert into t VALUES(this_year()); Binary…
Post: Profiling MySQL Memory Usage With Valgrind Massif
January 9, 2013 By 3 Comments
… releases [better] support newer hardware and software. Once ‘valgrind –version’ returns the correct installed version, you’re ready to go. In… allocation functions) malloc/new/new[], –alloc-fns, etc. ->50.57% (35,728,995B) 0x7A3CB0: my_malloc (in /usr/local/percona/mysql-5… allocation functions) malloc/new/new[], –alloc-fns, etc. ->84.91% (349,404,796B) 0x7A3CB0: my_malloc (in /usr/local/percona/mysql-5…
Post: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
… as only actual rows which are found and returned up to the top level MySQL part for processing are counted the Rows… about in this case is removing group by and aggregate functions. Then query would become “select * from sbtest” which would send… many rows query sends after group by, distinct and aggregate functions are removed (A) – look at number of rows examined divided…
Post: MySQL opening .frm even when table is in table definition cache
November 21, 2011 By 8 Comments
… shows. In MySQL 5.5 you can find in sql/datadict.cc a function named dd_frm_type(). In MySQL 5.1, for… the deep history of the FRM file format to confirm) return the fourth byte for the DB_TYPE. i.e. what… InnoDB itself and in the table_definition_cache). Further reading: MySQL Forge Internals document on the FRM file format Stewart’s…
Post: Percona Toolkit by example - pt-stalk
January 3, 2013 By 3 Comments
…have pt-stalk running 24/7, because problems such as MySQL lockups or spikes of activity typically leave no evidence …the function called trg_plugin inside the script ./pt-stalk-function (–function ../pt-stalk-function) return more than 100 (–threshold 100) $ pt-stalk –function ./pt-stalk-function…
Post: Stored Function to generate Sequences
April 2, 2008 By 17 Comments
… function seq(seq_name char (20)) returns int begin update seq set val=last_insert_id(val+1) where name=seq_name; return…. This way of using this function allows you to “inject” the value to be returned next time this function is called. Sometimes people wonder why you would like to use sequences instead of MySQL auto…
